Why is placement of your dimension important

When dimensions will not fit in a space in the usual way, other methods are used to dimension clearly, when those crowded conditions exist. Arrowheads are placed at each end of dimension lines, on leader lines, etc.

Usually they have a slight barb, much like a fishhook. Again, it is particularly important that the numbers and fractions you may put on a sketch or drawing be legible. Sloppy numbers can cause expensive mistakes. Notes are used on drawings to provide supplementary information. They should be brief and carefully worded to avoid being misinterpreted, and located on the sketch in an uncrowded area.

The leader lines going to the note should be kept short. Notes are usually added after a sketch has been dimensioned to avoid interference with dimensions. Oblique dimensioning is mostly remembering to avoid dimensioning on the object itself when possible and the use of common sense dimensioning principles. It is also usually best to have dimensions read from the bottom unidirectional as shown here.

Although it is best not to dimension on the view itself, its usually accepted practice to place diameter and radius dimension on the views if space permits. Sometime space and time is limited and you might have to bend the typical rules of drawing and dimensioning. The most important thing is to keep the drawing clean, concise, try to not a repeat dimensions but give all required ones.

Dimension the drawing. When dimensioning an isometric sketch, it is important to keep dimensions away from the object itself, and to place the dimension on the same plane as the surface of the object being dimensioned. You will probably find that to dimension well in isometric will take some practice. Place notes on an isometric drawing without regard to placing them on the same plane, as with dimensions.

It is easier to do, and easier to read. Notice in the example above that part of each leader line to the notes are sketched at an approximate angle of 15, 30, 45, 60 or 75 degrees.

This is done to avoid confusion with other lines. Never draw leader lines entirely horizontal or vertical.

Completeness: nothing must be left out, and nothing duplicated. Readability: the appropriate line quality must be used for legibility. The Basics:. Definitions and Dimensions. The dimension line is a thin line, broken in the middle to allow the placement of the dimension value, with arrowheads at each end see diagram below.

An arrowhead is approximately 3 mm long and 1mm wide. Leader or Pointer Lines: These are thin continuous lines drawn from a dimension figure to the feature to which it refers. Dimension Figure: These are drawn may be vertical or inclined to indicate the height of the dimension figure. The dimension unit is millimetre. The unit of the dimension is omitted while writing the dimension fig. Circular features like cylindrical parts like shafts, pipes, rods or any other round shape are always dimensioned by indicating their diameter.

Because it is easily measured. The diameters on the circular objects may be indicated in any one of the following ways as shown in fig. The curved, fillets and round figures are shown in drawings by arcs or circles. The dimensioning is done by giving radii. The measured radius is indicated by letter R. The dimension line is drawn radial with the arrowhead touching the arc. When the centre is located by the projection lines, the centre shall be marked by a clear dot and the arrowhead may be reversed.

When the centre of the arc falls outside the drawing limit, the dimension line of the radius should be broken or interrupted according to whether or not it located the centres.

When dimensioning the length of an arc the dimension figure identified by symbol being written above the dimension. It is a linear distance between any two points of an arc.

And it is dimensioned as shown in the figure. There are two types of dimensioning systems one is Aligned system and another is Unidirectional system. In this type of dimensioning systems, Dimensions are placed above the dimension lines which are drawn without any break and written parallel to them.

That they may be read from the bottom or any other side of the drawing sheet. Dimensions are placed in the middle and on top of the dimension lines. In this type of dimensioning system, dimensions are placed in such a way that they can be read from the bottom edge of the drawing sheet.

Dimensions are inserts by breaking the dimension lines at the middle. Use only one placing of dimension system in one entire drawing. The aligned and unidirectional system should not be mixed together in one drawing. Chain dimensioning is a dimensioning system that dimensions from point to point.

Or it is a series of adjacent dimensions are arranged in one horizontal row. When chain dimensioning is used the location of one feature is based on the location of the previous feature from which it is dimensioned.

Chain dimensioning is used when it is important that two features are located at a certain distance from each other. For example, Two fixed holes with two fixed pins may require a certain distance from each other to draw chain dimensions. When the number of dimensions is measured in the same direction from a common surface or line.